http://www.wastewaternews.org/2010/02/taking-green-to-extreme.html

This elite NYC highrise makes use of a system which recycles wastewater.  Treated wastewater is recirculated for use in cooling towers and toilets; likewise, water from washing machines and showers is also treated and reused.  The process manages to recycle about 25000 gallons per day; considering the average 120 gpd/person, this is a significantly effective system.

Fantastic to see such a dedicated effort at water conservation!